The Smart Power Measuring Sensor (SPMS) uses a dedicated microprocessor in the package to provide analog to digital conversion, calibration, and preparation of serial data for delivery to a host computer over a two wire modulated carrier system. Power is obtained from the voltage being measured and a current sensor is built into each unit. Data is transmitted over a standard interface such as RS232 or RS485. Transformer coupling is used to provide isolation required by regulations.
Smart Sensors are potted environmentally rugged units. Each contains an inductive sensor of patented SRT design. The output of the sensor is scaled, compensated for temperature and phase, and synchronized with the line to enable measurements through the 64th harmonic. Multiple sensors can be connected for three phase power monitoring.
The SPMS units are programmable by the user for special tasks. A host computer
downloads software to the sensor and then makes periodic requests of each sensor
and uses the results as required. Calibration constants and a unique identification
are permanently stored in ROM within each sensor. Code and data are stored within
each sensor in nonvolatile 32K RAM which retains data for recovery by a host
following a power failure. The SPMS measures both voltage and current for a
stand alone system where single and three phase monitoring is needed. The SPMS
is excellent for monitoring instantaneous and rms AC voltage, Power Factoring
(real power vs. reactive power), energy consumption, current and voltage wave
form samples up to 20 kHz, and instantaneous peak voltage
to 20 times full scale. Software for the SPMS is downloaded by the host and
may be rewritten in less than two seconds. Boxcar integration with samples
synchronized with phase and voltage averaged will allow precision which
increases with time. Five seconds corresponds to 16 bits at 60Hz.
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We've made available a downloadable .PDF file which illustrates how the SPMS is configured for three phase wye and delta systems. To view .PDF files you need Adobe Acrobat Reader. Adobe Reader is freeware which can be downloaded off their internet site at www.adobe.com.
If you wish to inquire about our Smart Sensor, you might want to look at our short SPMS questionnaire first. It's a list of the type questions we would need answered for an SPMS installation.
Engineers at SRT are available to discuss any questions you might have on any of
our products. Often we are asked to customize or prepare special calibrations on
our sensors to suit customer needs. Please contact us at (800) 447-6805 and ask
for Dayle Smith or Doug McNutt, or FAX us at (719) 634-2601, or send E-mail